[Kamailio-Users] AVP problem

Hello list. I'm getting this error trying to start the kamailio process /usr/local/sbin/kamailio[29243]: INFO:core:init_mod: initializing module mediaproxy /usr/local/sbin/kamailio[29243]: ERROR:core:pv_parse_spec: error searching pvar "avp" /usr/local/sbin/kamailio[29243]: ERROR:core:pv_parse_spec: wrong char [s/115] in [$avp(s:signaling_ip)] at [5 (5)] /usr/local/sbin/kamailio[29243]: CRITICAL:mediaproxy:mod_init: invalid AVP specification for signaling_ip_avp: `$avp(s:signaling_ip)' /usr/local/sbin/kamailio[29243]: ERROR:core:init_mod: failed to initialize module mediaproxy This is the line in the kamailio.cfg file : modparam("mediaproxy", "signaling_ip_avp", "$avp(s:signaling_ip)") I'm using kamailio 1.5.2 What I'm missing here?. Thanks, Ricardo Martinez